Especially for viscous liquids such as fuel oil, it is prudent practice to remove non-combustible particulates before storing the liquid, and especially before feeding it to a combustion system. In-line filters have long been used for this purpose. The advantages of fine filtering of other liquids such as water and solvents are also well-known, and such applications are contemplated herein.
The potential disadvantages of in-line filters are well-known, and are largely centered on the ultimate reduction of efficiency caused by the plugging of the filter pores, and the difficulty of removing the separated particulates from a closed system. One common technique is to provide two filters in parallel circuitry with one another. While one side is open to filtered flow, the other side is closed and backwashed. It is, of course, also possible to shut down a system for backwash and purge of particulates at the cost of down time. The saving of downtime is reduced by the cost of duplicating filtration facilities.
It is an object of this invention to provide a porous ceramic filter which by its own vibrations can release from its surface the particulates that are detained by it, to provide a swirling motion in the stream to sweep the filter surface, and to provide a periodically actuated purge circuit to remove particulates from the stream just upstream from the filter surface.